Form clamping device



Patented Oct. 9, 1962 3,057,034 FORM CLAMPIN G DEVICE Donald E. Helmick, 592 W. Barstow, Fresno, Calif. Filed June 5, 1961, Ser. No. 114,757 Claims. (Cl. 25131) The present invention relates to a clamp to maintain the spaced relationship of the walls of mold forms. It is particularly adapted for use in maintaining such walls used to mold concrete which must be vibrated during the pouring operation to preclude the possibility of voids occurring in the hardened concrete.

In the construction of concrete foundation walls, it is the conventional practice to erect and to support spaced wall defining members to receive concrete for setting in the desired shape. The walls are normally constructed of wood, and upright studs are used to support the outside of the form walls. Horizontal stringers, or walers, are extended transversely of and outwardly against the studs to be engaged by a form clamp to maintain a prede termined relationship.

Several types of clamps have been utilized in the past for spacing and clamping a pair of opposed form walls. The usual form of such clamps is a tension member extending through both walls and adapted to be engaged by a pair of adjustable stops which are moved inwardly to press the walls against a strut used as a spacer. Many of the clamps employ a screw-threaded connection either within the body of the strut or at the connection between the tension member and adjustable stop. Such connections are undesirable in that wrenches are usually necessary in their assembly and disassembly and the threaded connections are prone to oxidize when subjected to the wet concrete and dampness in the areas immediately adjacent to the concrete. These shortcomings are particularly objectionable during removal of the forms since they cause an undue amount of delay as well as possible damage to the concrete walls when the threaded connections are unscrewed. In addition, many of the clamps now in use are not designed to permit ready removal of the strut member used to space the form walls.

During the pouring of concrete in a plastic condition, it is quite often necessary to vibrate the concrete as it is poured into the form to insure that all of the space within the form is completely filled. If the concrete is not vibrated, particularly in the case of complex forms, voids frequently occur. Therefore, to insure a completely filled form, a mechanical or electrical vibrator, wellknown to those skilled in the art of erecting concrete walls, dams, and the like, is used as a source of vibration. Power driven vibrators are normally used to induce a settling action of the concrete and consequently impart a vibratory motion to the walls of the form. This vibration quite frequently loosens the adjustable stops at the outer ends of the tension member of the form clamp. In particular, those clamps which employ tapered wedges on the stop members are quite prone to loosen during the vibrating of the form wall.

Accordingly, it is an object of the present invention to provide an improved form clamp which is easily assembled and disassembled without the need for special tools.

Another object is to provide a clamp for the walls of a form which will maintain them in an assembled relation during the pouring and setting of concrete which must be subjected to vibration during the initial period of moldmg.

' Another object is to provide a form clamp which may be retrieved from the form and the material molded therein.

Another object is to provide a clamp for use with forms to mold a concrete wall which meets standard specifications for clamps of this type.

These, together with other objects, will become more fully apparent upon reference to the following description and accompanying drawing.

In the drawing:

FIG. 1 is a fragmentary side elevation of a form showing the form clamp embodying the principles of the present invention.

FIG. 2 is a transverse, vertical section taken on line 22 of FIG. 1.

FIG. 3 is a horizontal section taken on line 33 of FIG. 1.

FIG. 4 is a front elevation of a wedge adapted for use with the tie rod tension member of FIGS. 2 and 3.

FIG. 5 is a fragmentary view in elevation of an end of the tie rod adapted to be engaged by the wedge of FIG. 4.

FIG. 6 is a perspective view, somewhat enlarged, of the releasable cam lock of the clamp of FIG. 3.

FIG. 7 is a perspective view, somewhat enlarged, of the wedge of HG. 3.

Referring to the drawing, a form commonly used to mold concrete is generally indicated by the numeral 10 and is supported on the ground indicated at 11. The form includes a pair of elongated, horizontal base plates 12 rested on the ground in transversely spaced relation and a pair of opposed form walls 13 secured to their respective base plates so as to define a mold cavity therebetween.

In conventional practice, studs 20 are secured to the base plates 12 and extended upwardly along the outside of the form walls 13. The component parts of the forms are normally fastened by means of nails 21. Vertically spaced pairs of elongated stringers or walers 22 are extended along the studs in upwardly spaced relation to the base plates to serve as pressure members in maintaining desired spacing of the form walls. The stringers are located in substantially common horizontal planes ex tended transversely of the cavity. The form wall and stud on opposite sides of the cavity provide axially aligned bores identified by the numeral 25. The bores in corresponding studs on opposite sides of the cavity are also in axial alignment.

A form clamp embodying the principles of the present invention is generally indicated by the numeral 30 and includes an elongated tubular spacing strut 31 having an external frusto-conical surface 32 terminating in opposite ends 33 and 34 of maximum and minimum diameter respectively. The spacer i provided with a longitudinally extending bore 35 having a diameter substantially coincident with bores 25. The ends 33 and 34 are both of a larger diameter than the bores 25 and provide a peripheral flat area for the purpose of contacting the opposed walls of the form. Spacer 31 thereby serves as a strut when the clamp i positioned on the concrete form.

The clamp 30 also includes an elongated cylindrical tension rod 41 slightly smaller in diameter than the bores 25 so as to be slidably receivable therein. At least one end indicated at 41 of the tension rod is provided with one or more pairs of opposed traverse slots 42. The outer wall of each transverse slot is curved to form an inwardly facing convex shoulder 43. The shoulder thus formed is substantially normal to the longitudinal axis of rod 40. Accordingly, the midpoint of shoulder 43 is nearest to the form wallwith the clamp in an assembled position, as can be seen in FIG. 2.

The clamp 39 includes a wedge plate 50 best illustrated in FIGS. 2, 4 and 7. The plate includes a keyhole shaped slot 51 extending longitudinally of the plate. The enlarged portion of the slot is adapted to receive the end of the rod 40. A narrower portion is defined by a pair of opposed wedging elements 52 extended longitudinally on the wedge plate. Each wedging element is provided with a plurality of contiguous arcuate recesses, or sockets, 53 which present a concavely-formed surface facing outwardly and adapted to engage the convexly-shaped shoulders 43 of the rod end. -In the preferred form, each of the recesses 53 constitute a concave socket which is disposed in relation to the wall-engaging side 54 of the wedge plate so that the central portion 55 is disposed from the surface 54 a distance less than the longitudinally spaced terminal portions 56 of each socket defined by promontories 57. The construction of the wedge plates, particularly the disposition of the recesses on the wedging members, is important to insure that the wedging clamp does not become loosened during the agitation of the concrete by power driven vibrators commonly used for such operation. The wedge plate is preferably made of steel having a modulus of elasticity approaching that of spring steel. With such a construction, the wedge plate may be securely driven into position, as shown in FIGS. 2 and 3, so that the wedge members 52 are in a stressed condition after assembly. The energy stored in the spring material is therefore capable of exerting a continuous force on the tension member. Accordingly, the interfitting shoulders 43 and recesses 53 maintain the wedge plate in a selected transversely adjusted position with respect to the rod 40.

The opposite end of the rod 40 may be detachably secured with respect to the waler member 22 on the opposite side of the form by any suitable means such as wedge plate 50 described above. However, in the preferred form of the clamp 30, a quick-release cam lock is provided to adjust readily the effective length of the rod, as well as to facilitate removal of the clamp. A quickrelease cam lock, generally indicated at 69 includes a stop plate member 61 provided with a suitable bore 62 which receives the end of the rod 40. An upright wall 63 projects outwardly from the plate member to provide a support for a cam locking member 64 eccentrically mounted therein by means of a pin 65. The cam includes an operating handle 66 engaged by a spring 67 carried on wall 63 to urge the periphery of the cam into locking engagement with the rod. That portion of the cam which normally engages the rod may be provided with serrations 68 to grip the rod more firmly and prevent inward movement thereof to maintain the form walls in their spaced relationship. The cam may be easily rotated in a clockwise direction, as viewed in FIG. 2, to compress biasing spring 67 and disengage serrations 68 from the rod as the cam rotates about the eccentrically positioned pin 65. This permits removal of cam lock 60 from rod 40. The rod may then be withdrawn from the opposite side of the form and separated from wedge plate 50.

Operation The operation of the described embodiment of the subject invention is belived to be readily apparent and is briefly summarized at this point. Prior to assembly of the form 10, a spacer tube 31 is selected to conform to the desired width of the cavity defined by walls 13. The spacer is then positioned with its longitudinal bore 35 in axial alignment with bores so that the opposite ends 33 and 34 of the spacer abut the walls 13 as shown in FIGS. 2 and 3.-

The rod 40 is then extended through the bores 25 of the studs 20 in the form walls 13, through the spacer 31 until it projects outwardly from the opposite wall. The waler members 22 are then positioned above and below the rod 40 prior to locking the clamp in place. The slotted end 41 of the rod is then passed through the enlarged portion of the slot 51 and wedge plate 50. If a plurality of spacer slots are provided on the rod so that the clamp may be used with cavities of various widths, that slot which conforms to the width of the form is selected. The wedge member is then adjusted transversely with respect to the rod 50 that a pair of opposed Normally the wedge plate is adjusted initially to a position so that the pair of recesses immediately adjacent the enlarged portion of the slot are in engagement with the shoulders 43 of the rod.

A stop member, such as the cam lock 60 or another wedge plate 50, is then secured to one end of the rod to define one of the axial limits of the clamp. Wedge plate 50 is then further adjusted transversely with respect to the rod 45 so that any desired tension force may be applied to the clamp. Moving the wedge plate to such an adjusted position tends to compress the wedge members 52. The reaction force induced in the elastic wedge member in cooperation with shoulders 43 and interfitting recesses 53 is effective to maintain the clamp in a stressed condition.

After the form 10 has been assembled and clamped in the manner described above, moldable material in a plastic or amorphic form, not shown but such as concrete, is poured into the cavity between the form Walls 13 and allowed to harden or set. In this manner the spacers 31 become embedded in the concrete formed in the cavity.

After the concrete has hardened, the cam lock 60 is released quite easily by rotation in a clockwise direction, as shown in FIG. 2. The rod 40 may then be withdrawn from the right, as viewed. If supplementary means, such as the nails '70, are used temporarily to hold the locking members in place, these must be removed prior to release of the clamp 30.

After removal of the clamp 30 and the waler members 22, the wall forms 13 are then stripped from the hardened concrete. The spacers 31 may then be removed quite readily by tapping the end 34 of minimum diameter which slide the spacer outwardly from the foundation wall. The resulting frusto-conical bore in the wall may then be filled, if desired.

The clamp 30 is of extremely sturdy and economical construction and facilitates the assembly and dismantling of concrete forms. A particular advantage is the complete absence of any screw-threaded connections which are prone to oxidize and corrode when subjected to wet concrete. A significant feature of the clamp is its ability to withstand vibrations imparted thereto by the power driven mechanisms used to agitate the concrete during the settling process. With clamps of conventional design employing a plane surface on the wedging member, such vibration quite easily loosens the clamp to permit the form walls to separate from the ends of the spacer and ultimately preclude removal of the spacer. The force of the rod in tension is free to act upon the inclined plane surface of such a wedge, which tends to urge the wedge toward a release-d position. However, with the wedge plate 50 of the present invention, the tension in the rod member 40 is utilized in conjunction with recesses 53 engaging the shoulders 43 of the rod positively to maintain the wedge in a predetermined adjusted position. This insures that the clamp 30 will not loosen during the severe vibration imparted during the agitation process. By using an adjustable stop member, such as the cam lock 60, in com bination with the wedge plate 50, the clamp may be readily adjusted for forms of various widths. A clamp embodying the present invention may also be released readily upon subsequent dismantling of the forms.

Although the invention has been herein shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope of the invention, which is not to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent devices and apparatus.

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In a clamp for spacing a pair of spaced opposed form walls, wherein the clamp includes an elongated rod axially extended through and projected outwardly from the walls, the rod having at least one end provided with a pair of laterally opposed, transversely extended slots, means for limiting the axial inward movement of said one rod end comprising the combination of a pair of laterally opposed inwardly facing convex shoulders formed in said rod end, each shoulder having predetermined limits thereby defining an outer wall of each of the slots, and a wedge plate provided with a longitudinally extended keyhole slot and having a Wall engaging surface and a pair of spaced laterally opposed wedging elements arranged on opposite sides of the slot, each wedging element providing an outwardly presented engaging surface opposite from the wall engaging surface, said wedging element being adapted to embrace the slotted portion of the rod, and said outwardly presented surface being formed with a plurality of longitudinally spaced promontories defining contiguous, concave, arcuate, transverse recesses in said surface and adapted to engage said shoulders in the rod.

2. In the clamp structure of claim 1 wherein the spaced promontories provided on the engaging surface of each wedging element are disposed to define the longitudinal boundaries of said recesses coterminous with the corresponding limits of said shoulders on the rod, and the convex shoulders are engaged by and in substantial intimate contact with a pair of recesses in said surfaces of the wedging elements.

3. In a clamp for maintaining a pair of form walls in spaced, opposed relationship and having an elongated rod axially extended through and projected outwardly from the walls, at least one end of the rod having a slotted portion provided with a pair of laterally opposed, transversely extended slots, the combination of a pair of laterally opposed, inwardly facing convex shoulders formed in said end of the rod and each defining the outer wall of said slots, and a wedge plate provided with a longitudinally extended keyhole slot and having a wall engaging side providing a surface disposed substantially normal to the longitudinal axis of the rod and a pair of tapered, longitudinally extended wedging elements arranged on opposite sides of the keyhole slot, adapted to embrace said slotted portion of the rod, and providing an outwardly presented engaging surface opposite from the wall engaging side, the engaging surface of the wedging elements being provided with a plurality of concave sockets extended transversely of the wedging elements and being of a longitudinal dimension adapted for selective engagement with said shoulders to maintain a predetermined transversely adjusted position of the wedge member with respect to the rod, the longitudinal dimensions of said sockets being defined by longitudinally spaced promontories provided on the wedinging elements, and each of said sockets having a central portion and longitudinally spaced terminal portions, the central portion being spaced from said wall engaging surface a distance less than the terminal portions.

4. For use with an elongated rod in a form clamp, a wedge plate of a substantially rectangular configuration in plan, having a first wall engaging surface and an opposite rod engaging surface, the wall engaging surface lying in a first plane and the rod engaging surface lying generally in a second plane disposed at an acute angle with respect to the first, said rod engaging surface being afforded by a pair of longitudinally extended, laterally opposed wedging elements integral with the wedge plate, the plate having a longitudinally extended keyhole slot embraced by the wedging elements and adapted to receive said rod, the rod engaging surface of each of the wedging elements being provided with a plurality of promontories longitudinally spaced at regular intervals to define longitudinal limits of arcuate recesses provided therebetween, said recesses being outwardly concave to provide a central portion lying more closely to the Wall engaging surface than said longitudinal limits.

5. For use in a form clamp having an elongated rod provided with at least one end of slotted configuration thereby affording laterally opposed convex shoulders facing the midportion of the rod, a wedge plate formed of a resilient spring steel and having a first wall engaging surface lying in a first plane and a pair of tapered, longitudinally extended wedging elements formed integrally with the plate and providing a rod engaging surface lying generally in a plane disposed at an acute angle with respect to the first plane, the plate having a keyhole slot longitudinally extended between the wedging elements and adapted to receive said slotted end of the rod, the rod engaging surface provided by the wedging elements being formed with laterally opposed promontories longitudinally spaced at regular intervals corresponding to the limits of said convex shoulders of the rod and providing outwardly facing concave sockets between the promontories and adapted to receive the shoulders, the concave sockets each having terminal portions embracing a central portion, the central portion disposed more closely adjacent to the wall engaging surface than the terminal portions, whereby when the wedge plate is stressed in compression between the wall engaging surface and the rod engaging surface by the convex shoulders of the rod, the concave sockets of the rod engaging surface in conjunction with the shoulders maintain a previously selected position of transverse adjustment of the Wedge plate relative to the rod.

References Cited in the file of this patent UNITED STATES PATENTS 1,990,234 Kemper Feb. 5, 1935 2,190,700 Colt Feb. 20, 1940 2,494,423 Wright Jan. 10, 1950 2,709,292 Otti May 31, 1955 2,772,596 Trussell Dec. 4, 1956 FOREIGN PATENTS 546,800 Italy Aug. 1, 1956 145,078 Switzerland Feb. 15, 1931 

